All-metal sandwich panels, made by a process of laser welding faceplates to core-stiffeners, show advanced cost/weight properties compared with the conventional structural applications of stiffened plates. However optimal design of these advanced structures requires a fast simulation procedure that should have the same level of reliability compared to finite element calculations and natural tests, while being more time effective and less complex. It was shown that different polynomial functions together with design of computer experiments can contribute to such an aim by providing simple however reliable metamodels. The validation procedure indicated an average of 10% relative root mean square error prediction accuracy, and due to this precision the procedure is capable to be used for further (cost/weight) design optimisation together with structural sizing studies and parametric sensitivity analysis.